The invention relates to electronic fuel-injection circuitry for internal-combustion engines and is more particularly concerned with generation of suitable throttle-responsive fuel-flow control signals used in such circuitry.
Reference is made to my U.S. Pat. Nos. 3,305,351 and 4,349,000 for detailed discussion of pulse-width modulating circuitry for operation of the solenoids of fuel-injectors in a variety of engines of the character indicated. The disclosure in said patents, for example in connection with FIG. 6 of said U.S. Pat. No. 4,349,000, is concerned with circuit accommodation of various input parameters, in the form of analog voltages which reflect air-mass flow for the current engine speed, and a correction is made for volumetric efficiency of the particular engine, to arrive at a pulse-width modulating voltage E.sub.MOD. in a line to each of two like square-wave pulse generators. These pulse generators respectively serve for fuel-injection control in different groups of cylinders in the involved engine. The input parameters include engine speed and throttle setting, and the disclosure is for a potentiometer to track throttle setting, which is the customary provision for general public acceptability--i.e., for normal commercially satisfactory performance.
However, for racing performance, as when a marine outboard engine is expected to sustain operating speeds in excess of 6,000 rpm, there is such a short life for the best available throttle-tracking potentiometer as to jeopardize performance in a given race, and the potentiometer must be replaced altogether too often.